Gamma Ray Bursters

I've been searching the internet for a reasoanable explanation for the fenomenon and one observation of a GRB 8 billion light years from earth tranformed 1.3 times the mass of the sun into gamma radiation and 16 days later they detected a new blue galaxy with stars already forming. Can someone explain that??

Cor, that's a long way off. Can it harm us or touch us in some way or other?

From what I've read about this, a gamma ray burst approx. 6000 light years from earth that points in our direction may annihilate most or all the life on Earth.
But 8 billion light years away, no, it can't harm us. :)

Welcome to PF Zig! Indeed, we would not want a GRB to erupt anywhere near planet earth. Even one within 10,000 light years would be pretty scary. But we appear to be in luck. The nearest one to date has been around a billion light years distant. Scintillating to scientists, but not threatening.

As to a connection between ultra-high energy cosmic rays and GRBs? Stay tuned!

GRB's appear to be cosmologically distant, that is GRB after glows are high z. However, because of the significant energy loss by the GZK (Greisen-Zatsepin-Kuzmin 1966) mechanism, the present universe is not transparent to the highest energy cosmic rays (1020 eV), here.

Therefore any sources contributing to the bulk of these cosmic rays should be within 500 Mpc of earth for 1019 eV CR particles and a few ten's of Mpc for 1020 eV CR particles.

It would therefore seem to be difficult to sustain a connection between GRB's and the highest energy cosmic rays.

Welcome to PF Zig! Indeed, we would not want a GRB to erupt anywhere near planet earth. Even one within 10,000 light years would be pretty scary. But we appear to be in luck. The nearest one to date has been around a billion light years distant. Scintillating to scientists, but not threatening.

Thanks for the warm welcome, Chronos. :)

I've read about one hypernova only 25 million light years away from here, in the galaxy M74. The GRB didn't hit us though.

Also, I've heard about some very massive stars in our own galaxy only 5500 light years away that with a 50% or so probability will exterminate most life on Earth within 1 million years when they die.

GRB's appear to be cosmologically distant, that is GRB after glows are high z. However, because of the significant energy loss by the GZK (Greisen-Zatsepin-Kuzmin 1966) mechanism, the present universe is not transparent to the highest energy cosmic rays (1020 eV), here.

Therefore any sources contributing to the bulk of these cosmic rays should be within 500 Mpc of earth for 1019 eV CR particles and a few ten's of Mpc for 1020 eV CR particles.

It would therefore seem to be difficult to sustain a connection between GRB's and the highest energy cosmic rays.

That is one possible constraint Garth.

However, it seems http://www.aip.de/~jcg/grbrsh.html [Broken] GRBs are close enough to be, potentially, the source of the UHECR, and of course those below the GZK limit could travel much further.

Looking at GRBs a little more closely, we see that at least some long-soft ones are associated with (at least one kind of) core-collapse supernova, which we also know to occur at all kinds of distances. On top of that, despite the apparent association of one short-hard GRB with a giant elliptical (and so, possibly, a compact object merger scenario), the cause of these is far from settled (even the question of whether there's a single type of progenitor).

Finally, there's the question of quantity ... does anyone have a good paper they've seen that they'd like to share which compares estimates of likely/possible production rates with what we observe (mediated by flight times and mixmastering by magnetic fields)?

This CERN article has a few words about Centauro events (yes, they are indeed real, and may help us do particle physics in regimes that will be impossible for us to probe with accelerators we build for ourselves, such as the LHC, for decades or even centuries yet).

We are not imminently imperiled by any of our stellar neighbors. Eta Carinae, which is about 7500 light years away, is probably the nearest 'immediate' supernova threat. It is an enormous star, so it will put on quite a show. It is not, however, thought to pose any real threat to life on earth. Here is an article that may be of interest:http://www.space.com/scienceastronomy/supernova_threat_021216.html

It might not be a secret, but I had not heard that galaxies at high redshift (z~3-6 for instance) have a higher rate of supernovae production than lower-redshift galaxies. Wouldn't we have to see this for the initial statement to be supportable? If you can point me to some supporting evidence, I would be grateful.